Fine adjustment device for radio apparatus



Feb. .10, 1931. H. scHRcpDER 1,791,641

FINE ADJUSTMENT DEvIc'E FOR RADIO AiarAnA'rus Filed Dec. 11 1924 III/l. m

INVENTOR HEINFI H seaming, i

I RNEY when .considered with the Patented Feb. 10, 1931 UNITED STATES PATENT OFFICE nnnmrcn scnnonan, or BERLIN, GERMANY, assrenonv mo GESELLSOEAI'I run nmnrnosn rnnnemrnm M. B. n. namnsonns urea, or BERLIN, GERMANY,

A. CORPORATION OF GERMANY FINE ADJUSTMENT DEVICE FOR RADIO APPARATUS Application filed December 11, 1924, Serial no.

The present application relates to an arrangement for precise and fine adjustment of tuning means, as variable condensers, variometers, and the like, particularly. for amateur radio receivers. The arrangement guarantees special simplicity, cheapness and reliability. 4

These and other objects will be apparent from the following description andclaim's accompanying drawing in which:

Fig '1 is a section thru a panel showing the main dial forthe usualcourse adjustment with my improved device forgiving fine adjustment.

Fi 2 shows a detail of the structure of evice.

Fig. 3 is a section thru a panel showing my device, the section being at right angles to Fig 1.- ig. 4 is a section on the line 44'of- Fig. 1.

Referring to the drawing, P is the usual panel board having an opening 1 to accommodate shaft 2 of a piece of apparatus (not shown) mounted thereon. On the outer end of shaft 2 is the usual dial 1) and knob a for the usual course adjustment, the knob and diel being fixed to shaft 2 in any desired manner. The dial 6 has teeth 3 formed on its outer edge. y

Near the opening 1 isa second opening 4 for accommodating the shaft 5 and bent strip e. The plate 6 is fixed to the front side of panel P over 0 ening and has a slot ftherein running radially with respect to dial 1).

Fixed to plate 6 is bent elastic strip e shown developed in Fig. 2. Thelarger end of strip 6 is bent to provide a projection 7. This projection 7 is secured to plate 6 along one side of slot fin any-desired manner. The Y strip e is bent to form midway of its-length a bowed portion 8. The smaller end of strip e is bent to form a pro ectidn h, the function of which will be descri ed in detail below.

The shaft 5 has journals 9 and 10, the journal 9 turning in bearing- 11 formed in the bowed portion% andjournal 10 having rotative motion-an also sliding motion in slot f. The shaft 5 also has formed thereon a, spur 755,125, and in Germany December 20, 1923. a

which surface is bearing'on the reduced portion 13.

It will easily be understood that either cam surface 11 or 12 'may be selectively brought into bearing engagement with reduced portion-13 b forcing the knob c in either direction of ti; double pointed arrow a: against the thrus of the surface which happens to be operat n on it, until it overrides the intersectiono the surfaces 11 and 12. Also the projection ,h which is always in engagement with reduced portion 13 "effectively holds shaft 5 from movement longitudinally of its axis.

Therefore the resent application represents not only a simple arrangement for. ac-

curate adjustment of tuning means, but has the further advantage that: the arrangement at the same time is used for fixing the dial by means of a suitable gearing, so that no-un intended shifting ofthe dial can be caused by handling-the receiving apparatus. As the complete arrangement for Vernier adjust- ,rne'nt consists only'of a knob, a shaft, a s ring strip and a cover plate, it is very 0 cap.

Since the cam surface 12, when in engage- ,ment with reduced portion 13, always urges the gear 0! into engagement with the teeth 3 on 'dial b, this action takes care of any inaccuracyor eccentricity of the dial 6.

-Having describ d one embodiment of my invention, I am entitled to all modifications thereof as fall fairly within the scope ofthefollowing claims r 1. The combination {of a tuning dial with an adjustable Vernier adjustment device and a yieldab'le cam member having-two cam surfaces adapted to maintain said device in 0 erativeor inoperative relationship to said ial;

2. In combination, a rotary tuning dial, a Vernier adjustment device adapted to engage the periphery of said dial and a member for maintaining said vernier device in operative or inoperative position, saidmember being fixed at one end and provided at the other end with a cam face for engaging said Vernier device.

3. In combination, a rotary tuning dial, a vernier adjustment device adapted to engage the periphery of said dial and a yieldable cam member for continuously urging said device toward its operative or inoperative position.

4. In combination, a toothed rotary tuning dial, an adjustable vernier adjustment device comprising a knob having a depending cooperative gear and shaft, and a single yieldable means-:having a double cam surface at. one end, said camsurface acting to engage said shaft to maintain said device in either an operative or an inoperative relationship with v said dial. r

5. In combination, a toothed rotary tuning dial, an adjustable Vernier adjustment device comprising a knob having a depending cooperative gear and shaft, and a sin le yieldable means adapted to maintain said device in an operative or inoperative relationship with said dial, said means consisting of a slotted plate and a curved spring attachedthereto and forming a bearing for said shaft. 6.. In combination, a toothed rotary tuning dial, an adjustable vernier adjustment device comprisinga knob having a depending cooperative gear and' an annularly a grooved shaft, and .asingle yieldable means adapted to maintain said device in an operative or inoperative relationship with said dial, said means consisting of a slotted plate :and a 40 curved spring attached thereto and forming a bearing for saidshaft, said spring being adapted to contact with the grooved portion of said shaft.

7. The combination according to claim 6, in which said slotted plate is arranged with the slot radial to said .tuning dial, and in' which said curved .spring is attached at one end to said plate and is provided at its'free end with cam surfaces which act to move said shaft in said slot to maintain the operative or ino rative relationship between said dial an said device. I v

'8. In combination a'rotary element, a ver-' nier device for said element, said device being movable, into and out of operative osition, and a cam member fixed at one end or auto.' maticall urging said device toward the extr'eme 0 its moved position. i a IEINRIGH .SGHRUDER. 4 7 

